docs: def _get_loaded_modules():
          """Returns the modules which are enabled in Apache."""
          output = subprocess.check_output(['apache2ctl', '-M'])
          if six.PY3:
              output = output.decode('utf-8')
          modules = []
          for line in output.splitlines():
              # Each line of the enabled module output looks like:
              #  module_name (static|shared)
              # Plus a header line at the top of the output which is stripped
              # out by the regex.
              matcher = re.search(r'^ (\S*)_module (\S*)', line)
              if matcher:
                  modules.append(matcher.group(1))
          return modules